Electrochemical Synthesis of Cu₃(HHTP)₂ Metal-Organic Frameworks from Cu Nanoparticles for Chemiresistive Gas Sensing

The porosity of electrically conductive metal-organic frameworks (MOFs) make them attractive materials for use as the functional sensing element in a variety of electronic devices. Here, we present a route to reliably synthesize conductive MOFs uniformly and in situ through electrochemical growth of Cu₃(HHTP)₂ from Cu nanoparticle precursors. The nanoparticles are generated using a magnetron sputtering source and are deposited on glass substrates patterned with interdigitated electrodes. Subsequent solution-based electrochemical growth results in a uniform distribution of the MOF on the substrates as determined through Raman spectroscopy, XPS, SEM, and PXRD techniques. As a proof of concept, the MOF-decorated electrodes are then investigated as chemiresistive sensors for NO₂ and NH₃ gases. Sensing of NH₃ in dry N₂ carrier gas is achieved with a sub-ppm limit of detection.